Fuel nozzle head for anti-coking



Jan. 24, 1961 w. E. BLEVANS ETAL 2,968,925

FUEL NOZZLE HEAD FOR ANTI-COKING Filed Nov. 25. 1959 WILLIAM E. BLEVANS WALTER L. GRANT 2,968,925 FUEL NOZZLE HEAD FOR ANTI- IOKING William E. Blevans, Kansas City, Mo., and Walter L.

Grant, Overland Park, Kans., assignors, by mesne assignments, to the United States of America as represented by the Secretary of the Navy Filed Nov. 25, 1959, Ser. No. 855,432

4 Claims. (Cl. 6039.74)

The present invention relates to a fuel nozzle head for anti-coking and more particularly to a fuel nozzle head for anti-coking in a turbojet engine which prevents the building up of coke and carbon particles adjacent the end of the fuel nozzle.

Prior to this invention it has been common practice in the art to have an air cap pressfitted over the head of the fuel nozzle. This air cap served as an air deflector, deflecting air into the fuel spray and then into the cornbustion chamber. The fuel nozzle was provided with drilled passages to communicate air to the inside of the air cap or deflector and a fuel discharge orifice. This works well to the extent that the nozzle discharge orifice is kept clean and free of coke. However, after several hours of engine running, coke and carbon buildup occurs on the outside face of the cap or deflector forming a cone roughly the same shape as the fuel spray cone. This coke and carbon buildup has been found to cause deterioration of the fuel spray pattern in many instances.

The present invention contemplates the provision of making the nozzle head of unitary construction, thus eliminating the air cap, and having twelve drilled air passages communicating with an air deflector thereby performing the same function as the air cap previously used. However, in the instant application, an additional twelve air passages are drilled at a lesser angle than the first twelve air passages so as to direct air across the outside face of the air deflector, thus preventing the buildup of coke and carbon deposits.

Accordingly, it is a primary purpose of the instant invention to provide means for preventing buildup of coke and carbon deposits on fuel nozzles as used in conjunction with turbojet engines.

Another object is to provide a means for introducing air along the outside face of the air deflector or air guide whereby coke and carbon deposits are prevented from building up and distorting the fuel spray pattern.

A final object of the present invention is the provision of an additional set of air passages which direct air to the outside face of the air deflector or air guide and thereby preventing the building up of coke and carbon deposits and thus eliminating the problem of the distorted fuel spray pattern.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

Fig. 1 shows a plan view, partly in section, of a preferred embodiment of the invention.

Fig. 2 shows a section of the device taken on the line 2-2 of Fig. 1.

Referring now to the drawings, wherein like reference characters designate like or corresponding parts throughout the several views, there is shown in Fig. l a fuel nozzle 3 having at one end a fuelnozzle head 4 with a fuel injection orifice 5. Air from a source of supply (not shown) enters a" first air guide 18 wh ich confines the air in a' main air flow passage 6 and directs it to the nozzle head 42 Then'ozzle head 4 extends through an aperture 11 in the combustor housing 12. The nozzle head 4 is fixedly secured as at 17 by threads, or the like, to the fuel nozzle 3 and is provided with twelve equally spaced primary air passages 7 drilled at an angle to the main air flow passage 6 and terminates at a point where the air which is flowing therethrough will strike the inside face 19 of the second air guide or air deflector 9 and intermiX with the fuel spray to be injected into the combustion chamber 16. At a lesser angle to the main air flow passage 6 is another series of twelve secondary air passages 8 which communicate air to the outside face 21 of the second air guide or air deflector 9. The inside portion of the nozzle head 4 is undercut at 13 to provide a shoulder which serves as a third air guide 14 and directs the air from the secondary air passages 8 back to the outside face 21 of the second air guide 9 and thus prevents the coke and carbon deposits from forming thereon. It is to be noted that the diameter of the shoulder or flange 14 is of lesser diameter than the second air guide 9 and as such does not interfere with the fuel spray pattern. Also, the outermost end of the nozzle head 4 which extends into the combustion chamber 16 is tapered as shown at 15 to allow for the expansion of the fuel spray pattern as it enters the combustion chamber 16. In Fig. l the solid arrows show the present air flow through the nozzle head 3 and the broken arrows indicate the added air flow as used in the instant application. Fig. 2, a section taken on line 2-2 of Fig. 1 shows the nozzle head 4 with the twelve radially disposed secondary air passages 8, the second air guide 9, the primary air passages 7 being shown in dotted lines since they are hidden by the second air guide 9 and in the center of the nozzle head 4 is the fuel injection orifice 5.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed is: l

1. The combination of a fuel injection nozzle and a combustion chamber housing comprising a fuel injection nozzle head, an outlet orifice in said nozzle head, a first air guide formed by said combustion housing, a second and third air guide, each formed in said nozzle head, said second air guide being located adjacent said outlet orifice and having an inside and an outside face, an aperture in said second air guide in axial alignment with said outlet orifice, said aperture being of larger diameter than said outlet orifice, fuel supply means connected to said nozzle head and air passage means for supplying air to said nozzle head whereby coke is prevented from building up on said second air guide.

2. The combination as claimed in claim 1, wherein said air passage means comprises a main air flow passage feeding a plurality of radially disposed primary air passages supplying air to said inside face of said second air guide and a plurality of radially disposed secondary air passages supplying air to said third air guide.

3. The combination as claimed in claim 2 wherein said first air guide forms an annular passage providing a path for the main air flow passage and said second air guide takes the form of an annular air deflector securedly mounted in said nozzle head at such an angle so as to have the incoming air from said primary air passage strike said inside face of said air deflector and deflect the air into the fuel spray as it is injected into said fuel combustion chamber.

4. The combination as claimed in claim 3 wherein said third air guide is formed by a machined undercut and shoulder portion adjacent the outlet of said second ary air passage, said third air guide being of larger diameter than said second air guide and being formed at such an angle as to have the incoming air from said secondary air passages strike said third air guide and be deflected to said outside face of said second air guide.

References Cited in the file of this patent UNITED STATES PATENTS Purchas Feb. 1, 1955 Benson Mar. 1, 1960 FOREIGN PATENTS France 2. Nov. 26, 1952 

